Suppose that the lower half of the concave mirror’s reflecting surface in the given figure is covered with an opaque (non-reflective) material. What effect will this have on the image of an object placed in front of the mirror?

A mobile phone lies along the principal axis of a concave mirror, as shown in the figure. Then,

An object is placed at $10$ cm in front of a concave mirror with a radius of curvature of $15$ cm. The magnification of the image is:
1. $-3$
2. $3$
3. $1$
4. $-1$

An object is placed at $5~\text{cm}$ in front of a concave mirror with a radius of curvature of $15~\text{cm}.$ The nature of the image is:

Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of $R= 2~\text{m}$. If the jogger is running at a speed of $5~\text{m/s}$, how fast does the image of the jogger appear to move when the jogger is $39~\text{m}$ away?
1. $5~\text{m/s}$
2. $\dfrac{1}{60}~\text{m/s}$
3. $\dfrac{1}{280}~\text{m/s}$
4. $10~\text{m/s}$

The earth takes $24~\text{h}$ to rotate once about its axis. How much time does the sun take to shift by $1^{\circ}$ when viewed from the earth?
1. $3~\text{minutes}$
2. $2~\text{minutes}$
3. $1~\text{minutes}$
4. $4~\text{minutes}$

Light from a point source in the air falls on a convex spherical glass surface (n = 1.5 and radius of curvature = 20 cm) of a glass medium which extends till infinity on other side . The distance of the light source from the glass surface is 100 cm. At what position the image is formed?

A magician during a show makes a glass lens with $n=1.47$ disappear in a trough of liquid. What is the refractive index of the liquid? 
1. $1.47$
2. $1.33$
3. $0.66$
4. $1.5$

If $f=0.5$ m for a glass lens, what is the power of the lens?
1. $+0.4$ D
2. $+4.0$ D
3. $+0.2$ D
4. $+2.0$ D

The radii of curvature of the faces of a double convex lens are $10$ cm and $15$ cm. Its focal length is $12$ cm. What is the refractive index of glass?
1. $1.3$
2. $1.2$
3. $1.5$
4. $1.4$